xref: /linux/kernel/acct.c (revision 2408a807bfc3f738850ef5ad5e3fd59d66168996)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  linux/kernel/acct.c
4  *
5  *  BSD Process Accounting for Linux
6  *
7  *  Author: Marco van Wieringen <mvw@planets.elm.net>
8  *
9  *  Some code based on ideas and code from:
10  *  Thomas K. Dyas <tdyas@eden.rutgers.edu>
11  *
12  *  This file implements BSD-style process accounting. Whenever any
13  *  process exits, an accounting record of type "struct acct" is
14  *  written to the file specified with the acct() system call. It is
15  *  up to user-level programs to do useful things with the accounting
16  *  log. The kernel just provides the raw accounting information.
17  *
18  * (C) Copyright 1995 - 1997 Marco van Wieringen - ELM Consultancy B.V.
19  *
20  *  Plugged two leaks. 1) It didn't return acct_file into the free_filps if
21  *  the file happened to be read-only. 2) If the accounting was suspended
22  *  due to the lack of space it happily allowed to reopen it and completely
23  *  lost the old acct_file. 3/10/98, Al Viro.
24  *
25  *  Now we silently close acct_file on attempt to reopen. Cleaned sys_acct().
26  *  XTerms and EMACS are manifestations of pure evil. 21/10/98, AV.
27  *
28  *  Fixed a nasty interaction with sys_umount(). If the accounting
29  *  was suspeneded we failed to stop it on umount(). Messy.
30  *  Another one: remount to readonly didn't stop accounting.
31  *	Question: what should we do if we have CAP_SYS_ADMIN but not
32  *  CAP_SYS_PACCT? Current code does the following: umount returns -EBUSY
33  *  unless we are messing with the root. In that case we are getting a
34  *  real mess with do_remount_sb(). 9/11/98, AV.
35  *
36  *  Fixed a bunch of races (and pair of leaks). Probably not the best way,
37  *  but this one obviously doesn't introduce deadlocks. Later. BTW, found
38  *  one race (and leak) in BSD implementation.
39  *  OK, that's better. ANOTHER race and leak in BSD variant. There always
40  *  is one more bug... 10/11/98, AV.
41  *
42  *	Oh, fsck... Oopsable SMP race in do_process_acct() - we must hold
43  * ->mmap_lock to walk the vma list of current->mm. Nasty, since it leaks
44  * a struct file opened for write. Fixed. 2/6/2000, AV.
45  */
46 
47 #include <linux/mm.h>
48 #include <linux/slab.h>
49 #include <linux/acct.h>
50 #include <linux/capability.h>
51 #include <linux/file.h>
52 #include <linux/tty.h>
53 #include <linux/security.h>
54 #include <linux/vfs.h>
55 #include <linux/jiffies.h>
56 #include <linux/times.h>
57 #include <linux/syscalls.h>
58 #include <linux/mount.h>
59 #include <linux/uaccess.h>
60 #include <linux/sched/cputime.h>
61 
62 #include <asm/div64.h>
63 #include <linux/pid_namespace.h>
64 #include <linux/fs_pin.h>
65 
66 /*
67  * These constants control the amount of freespace that suspend and
68  * resume the process accounting system, and the time delay between
69  * each check.
70  * Turned into sysctl-controllable parameters. AV, 12/11/98
71  */
72 
73 static int acct_parm[3] = {4, 2, 30};
74 #define RESUME		(acct_parm[0])	/* >foo% free space - resume */
75 #define SUSPEND		(acct_parm[1])	/* <foo% free space - suspend */
76 #define ACCT_TIMEOUT	(acct_parm[2])	/* foo second timeout between checks */
77 
78 #ifdef CONFIG_SYSCTL
79 static const struct ctl_table kern_acct_table[] = {
80 	{
81 		.procname       = "acct",
82 		.data           = &acct_parm,
83 		.maxlen         = 3*sizeof(int),
84 		.mode           = 0644,
85 		.proc_handler   = proc_dointvec,
86 	},
87 };
88 
kernel_acct_sysctls_init(void)89 static __init int kernel_acct_sysctls_init(void)
90 {
91 	register_sysctl_init("kernel", kern_acct_table);
92 	return 0;
93 }
94 late_initcall(kernel_acct_sysctls_init);
95 #endif /* CONFIG_SYSCTL */
96 
97 /*
98  * External references and all of the globals.
99  */
100 
101 struct bsd_acct_struct {
102 	struct fs_pin		pin;
103 	atomic_long_t		count;
104 	struct rcu_head		rcu;
105 	struct mutex		lock;
106 	bool			active;
107 	bool			check_space;
108 	unsigned long		needcheck;
109 	struct file		*file;
110 	struct pid_namespace	*ns;
111 	struct work_struct	work;
112 	struct completion	done;
113 	acct_t			ac;
114 };
115 
116 static void fill_ac(struct bsd_acct_struct *acct);
117 static void acct_write_process(struct bsd_acct_struct *acct);
118 
119 /*
120  * Check the amount of free space and suspend/resume accordingly.
121  */
check_free_space(struct bsd_acct_struct * acct)122 static bool check_free_space(struct bsd_acct_struct *acct)
123 {
124 	struct kstatfs sbuf;
125 
126 	if (!acct->check_space)
127 		return acct->active;
128 
129 	/* May block */
130 	if (vfs_statfs(&acct->file->f_path, &sbuf))
131 		return acct->active;
132 
133 	if (acct->active) {
134 		u64 suspend = sbuf.f_blocks * SUSPEND;
135 		do_div(suspend, 100);
136 		if (sbuf.f_bavail <= suspend) {
137 			acct->active = false;
138 			pr_info("Process accounting paused\n");
139 		}
140 	} else {
141 		u64 resume = sbuf.f_blocks * RESUME;
142 		do_div(resume, 100);
143 		if (sbuf.f_bavail >= resume) {
144 			acct->active = true;
145 			pr_info("Process accounting resumed\n");
146 		}
147 	}
148 
149 	acct->needcheck = jiffies + ACCT_TIMEOUT*HZ;
150 	return acct->active;
151 }
152 
acct_put(struct bsd_acct_struct * p)153 static void acct_put(struct bsd_acct_struct *p)
154 {
155 	if (atomic_long_dec_and_test(&p->count))
156 		kfree_rcu(p, rcu);
157 }
158 
to_acct(struct fs_pin * p)159 static inline struct bsd_acct_struct *to_acct(struct fs_pin *p)
160 {
161 	return p ? container_of(p, struct bsd_acct_struct, pin) : NULL;
162 }
163 
acct_get(struct pid_namespace * ns)164 static struct bsd_acct_struct *acct_get(struct pid_namespace *ns)
165 {
166 	struct bsd_acct_struct *res;
167 again:
168 	smp_rmb();
169 	rcu_read_lock();
170 	res = to_acct(READ_ONCE(ns->bacct));
171 	if (!res) {
172 		rcu_read_unlock();
173 		return NULL;
174 	}
175 	if (!atomic_long_inc_not_zero(&res->count)) {
176 		rcu_read_unlock();
177 		cpu_relax();
178 		goto again;
179 	}
180 	rcu_read_unlock();
181 	mutex_lock(&res->lock);
182 	if (res != to_acct(READ_ONCE(ns->bacct))) {
183 		mutex_unlock(&res->lock);
184 		acct_put(res);
185 		goto again;
186 	}
187 	return res;
188 }
189 
acct_pin_kill(struct fs_pin * pin)190 static void acct_pin_kill(struct fs_pin *pin)
191 {
192 	struct bsd_acct_struct *acct = to_acct(pin);
193 	mutex_lock(&acct->lock);
194 	/*
195 	 * Fill the accounting struct with the exiting task's info
196 	 * before punting to the workqueue.
197 	 */
198 	fill_ac(acct);
199 	schedule_work(&acct->work);
200 	wait_for_completion(&acct->done);
201 	cmpxchg(&acct->ns->bacct, pin, NULL);
202 	mutex_unlock(&acct->lock);
203 	pin_remove(pin);
204 	acct_put(acct);
205 }
206 
close_work(struct work_struct * work)207 static void close_work(struct work_struct *work)
208 {
209 	struct bsd_acct_struct *acct = container_of(work, struct bsd_acct_struct, work);
210 	struct file *file = acct->file;
211 
212 	/* We were fired by acct_pin_kill() which holds acct->lock. */
213 	acct_write_process(acct);
214 	if (file->f_op->flush)
215 		file->f_op->flush(file, NULL);
216 	__fput_sync(file);
217 	complete(&acct->done);
218 }
219 
acct_on(struct filename * pathname)220 static int acct_on(struct filename *pathname)
221 {
222 	struct file *file;
223 	struct vfsmount *mnt, *internal;
224 	struct pid_namespace *ns = task_active_pid_ns(current);
225 	struct bsd_acct_struct *acct;
226 	struct fs_pin *old;
227 	int err;
228 
229 	acct = kzalloc(sizeof(struct bsd_acct_struct), GFP_KERNEL);
230 	if (!acct)
231 		return -ENOMEM;
232 
233 	/* Difference from BSD - they don't do O_APPEND */
234 	file = file_open_name(pathname, O_WRONLY|O_APPEND|O_LARGEFILE, 0);
235 	if (IS_ERR(file)) {
236 		kfree(acct);
237 		return PTR_ERR(file);
238 	}
239 
240 	if (!S_ISREG(file_inode(file)->i_mode)) {
241 		kfree(acct);
242 		filp_close(file, NULL);
243 		return -EACCES;
244 	}
245 
246 	/* Exclude kernel kernel internal filesystems. */
247 	if (file_inode(file)->i_sb->s_flags & (SB_NOUSER | SB_KERNMOUNT)) {
248 		kfree(acct);
249 		filp_close(file, NULL);
250 		return -EINVAL;
251 	}
252 
253 	/* Exclude procfs and sysfs. */
254 	if (file_inode(file)->i_sb->s_iflags & SB_I_USERNS_VISIBLE) {
255 		kfree(acct);
256 		filp_close(file, NULL);
257 		return -EINVAL;
258 	}
259 
260 	if (!(file->f_mode & FMODE_CAN_WRITE)) {
261 		kfree(acct);
262 		filp_close(file, NULL);
263 		return -EIO;
264 	}
265 	internal = mnt_clone_internal(&file->f_path);
266 	if (IS_ERR(internal)) {
267 		kfree(acct);
268 		filp_close(file, NULL);
269 		return PTR_ERR(internal);
270 	}
271 	err = mnt_get_write_access(internal);
272 	if (err) {
273 		mntput(internal);
274 		kfree(acct);
275 		filp_close(file, NULL);
276 		return err;
277 	}
278 	mnt = file->f_path.mnt;
279 	file->f_path.mnt = internal;
280 
281 	atomic_long_set(&acct->count, 1);
282 	init_fs_pin(&acct->pin, acct_pin_kill);
283 	acct->file = file;
284 	acct->needcheck = jiffies;
285 	acct->ns = ns;
286 	mutex_init(&acct->lock);
287 	INIT_WORK(&acct->work, close_work);
288 	init_completion(&acct->done);
289 	mutex_lock_nested(&acct->lock, 1);	/* nobody has seen it yet */
290 	pin_insert(&acct->pin, mnt);
291 
292 	rcu_read_lock();
293 	old = xchg(&ns->bacct, &acct->pin);
294 	mutex_unlock(&acct->lock);
295 	pin_kill(old);
296 	mnt_put_write_access(mnt);
297 	mntput(mnt);
298 	return 0;
299 }
300 
301 static DEFINE_MUTEX(acct_on_mutex);
302 
303 /**
304  * sys_acct - enable/disable process accounting
305  * @name: file name for accounting records or NULL to shutdown accounting
306  *
307  * sys_acct() is the only system call needed to implement process
308  * accounting. It takes the name of the file where accounting records
309  * should be written. If the filename is NULL, accounting will be
310  * shutdown.
311  *
312  * Returns: 0 for success or negative errno values for failure.
313  */
SYSCALL_DEFINE1(acct,const char __user *,name)314 SYSCALL_DEFINE1(acct, const char __user *, name)
315 {
316 	int error = 0;
317 
318 	if (!capable(CAP_SYS_PACCT))
319 		return -EPERM;
320 
321 	if (name) {
322 		struct filename *tmp = getname(name);
323 
324 		if (IS_ERR(tmp))
325 			return PTR_ERR(tmp);
326 		mutex_lock(&acct_on_mutex);
327 		error = acct_on(tmp);
328 		mutex_unlock(&acct_on_mutex);
329 		putname(tmp);
330 	} else {
331 		rcu_read_lock();
332 		pin_kill(task_active_pid_ns(current)->bacct);
333 	}
334 
335 	return error;
336 }
337 
acct_exit_ns(struct pid_namespace * ns)338 void acct_exit_ns(struct pid_namespace *ns)
339 {
340 	rcu_read_lock();
341 	pin_kill(ns->bacct);
342 }
343 
344 /*
345  *  encode an u64 into a comp_t
346  *
347  *  This routine has been adopted from the encode_comp_t() function in
348  *  the kern_acct.c file of the FreeBSD operating system. The encoding
349  *  is a 13-bit fraction with a 3-bit (base 8) exponent.
350  */
351 
352 #define	MANTSIZE	13			/* 13 bit mantissa. */
353 #define	EXPSIZE		3			/* Base 8 (3 bit) exponent. */
354 #define	MAXFRACT	((1 << MANTSIZE) - 1)	/* Maximum fractional value. */
355 
encode_comp_t(u64 value)356 static comp_t encode_comp_t(u64 value)
357 {
358 	int exp, rnd;
359 
360 	exp = rnd = 0;
361 	while (value > MAXFRACT) {
362 		rnd = value & (1 << (EXPSIZE - 1));	/* Round up? */
363 		value >>= EXPSIZE;	/* Base 8 exponent == 3 bit shift. */
364 		exp++;
365 	}
366 
367 	/*
368 	 * If we need to round up, do it (and handle overflow correctly).
369 	 */
370 	if (rnd && (++value > MAXFRACT)) {
371 		value >>= EXPSIZE;
372 		exp++;
373 	}
374 
375 	if (exp > (((comp_t) ~0U) >> MANTSIZE))
376 		return (comp_t) ~0U;
377 	/*
378 	 * Clean it up and polish it off.
379 	 */
380 	exp <<= MANTSIZE;		/* Shift the exponent into place */
381 	exp += value;			/* and add on the mantissa. */
382 	return exp;
383 }
384 
385 #if ACCT_VERSION == 1 || ACCT_VERSION == 2
386 /*
387  * encode an u64 into a comp2_t (24 bits)
388  *
389  * Format: 5 bit base 2 exponent, 20 bits mantissa.
390  * The leading bit of the mantissa is not stored, but implied for
391  * non-zero exponents.
392  * Largest encodable value is 50 bits.
393  */
394 
395 #define MANTSIZE2       20                      /* 20 bit mantissa. */
396 #define EXPSIZE2        5                       /* 5 bit base 2 exponent. */
397 #define MAXFRACT2       ((1ul << MANTSIZE2) - 1) /* Maximum fractional value. */
398 #define MAXEXP2         ((1 << EXPSIZE2) - 1)    /* Maximum exponent. */
399 
encode_comp2_t(u64 value)400 static comp2_t encode_comp2_t(u64 value)
401 {
402 	int exp, rnd;
403 
404 	exp = (value > (MAXFRACT2>>1));
405 	rnd = 0;
406 	while (value > MAXFRACT2) {
407 		rnd = value & 1;
408 		value >>= 1;
409 		exp++;
410 	}
411 
412 	/*
413 	 * If we need to round up, do it (and handle overflow correctly).
414 	 */
415 	if (rnd && (++value > MAXFRACT2)) {
416 		value >>= 1;
417 		exp++;
418 	}
419 
420 	if (exp > MAXEXP2) {
421 		/* Overflow. Return largest representable number instead. */
422 		return (1ul << (MANTSIZE2+EXPSIZE2-1)) - 1;
423 	} else {
424 		return (value & (MAXFRACT2>>1)) | (exp << (MANTSIZE2-1));
425 	}
426 }
427 #elif ACCT_VERSION == 3
428 /*
429  * encode an u64 into a 32 bit IEEE float
430  */
encode_float(u64 value)431 static u32 encode_float(u64 value)
432 {
433 	unsigned exp = 190;
434 	unsigned u;
435 
436 	if (value == 0)
437 		return 0;
438 	while ((s64)value > 0) {
439 		value <<= 1;
440 		exp--;
441 	}
442 	u = (u32)(value >> 40) & 0x7fffffu;
443 	return u | (exp << 23);
444 }
445 #endif
446 
447 /*
448  *  Write an accounting entry for an exiting process
449  *
450  *  The acct_process() call is the workhorse of the process
451  *  accounting system. The struct acct is built here and then written
452  *  into the accounting file. This function should only be called from
453  *  do_exit() or when switching to a different output file.
454  */
455 
fill_ac(struct bsd_acct_struct * acct)456 static void fill_ac(struct bsd_acct_struct *acct)
457 {
458 	struct pacct_struct *pacct = &current->signal->pacct;
459 	struct file *file = acct->file;
460 	acct_t *ac = &acct->ac;
461 	u64 elapsed, run_time;
462 	time64_t btime;
463 	struct tty_struct *tty;
464 
465 	lockdep_assert_held(&acct->lock);
466 
467 	if (time_is_after_jiffies(acct->needcheck)) {
468 		acct->check_space = false;
469 
470 		/* Don't fill in @ac if nothing will be written. */
471 		if (!acct->active)
472 			return;
473 	} else {
474 		acct->check_space = true;
475 	}
476 
477 	/*
478 	 * Fill the accounting struct with the needed info as recorded
479 	 * by the different kernel functions.
480 	 */
481 	memset(ac, 0, sizeof(acct_t));
482 
483 	ac->ac_version = ACCT_VERSION | ACCT_BYTEORDER;
484 	strscpy(ac->ac_comm, current->comm, sizeof(ac->ac_comm));
485 
486 	/* calculate run_time in nsec*/
487 	run_time = ktime_get_ns();
488 	run_time -= current->group_leader->start_time;
489 	/* convert nsec -> AHZ */
490 	elapsed = nsec_to_AHZ(run_time);
491 #if ACCT_VERSION == 3
492 	ac->ac_etime = encode_float(elapsed);
493 #else
494 	ac->ac_etime = encode_comp_t(elapsed < (unsigned long) -1l ?
495 				(unsigned long) elapsed : (unsigned long) -1l);
496 #endif
497 #if ACCT_VERSION == 1 || ACCT_VERSION == 2
498 	{
499 		/* new enlarged etime field */
500 		comp2_t etime = encode_comp2_t(elapsed);
501 
502 		ac->ac_etime_hi = etime >> 16;
503 		ac->ac_etime_lo = (u16) etime;
504 	}
505 #endif
506 	do_div(elapsed, AHZ);
507 	btime = ktime_get_real_seconds() - elapsed;
508 	ac->ac_btime = clamp_t(time64_t, btime, 0, U32_MAX);
509 #if ACCT_VERSION == 2
510 	ac->ac_ahz = AHZ;
511 #endif
512 
513 	spin_lock_irq(&current->sighand->siglock);
514 	tty = current->signal->tty;	/* Safe as we hold the siglock */
515 	ac->ac_tty = tty ? old_encode_dev(tty_devnum(tty)) : 0;
516 	ac->ac_utime = encode_comp_t(nsec_to_AHZ(pacct->ac_utime));
517 	ac->ac_stime = encode_comp_t(nsec_to_AHZ(pacct->ac_stime));
518 	ac->ac_flag = pacct->ac_flag;
519 	ac->ac_mem = encode_comp_t(pacct->ac_mem);
520 	ac->ac_minflt = encode_comp_t(pacct->ac_minflt);
521 	ac->ac_majflt = encode_comp_t(pacct->ac_majflt);
522 	ac->ac_exitcode = pacct->ac_exitcode;
523 	spin_unlock_irq(&current->sighand->siglock);
524 
525 	/* we really need to bite the bullet and change layout */
526 	ac->ac_uid = from_kuid_munged(file->f_cred->user_ns, current_uid());
527 	ac->ac_gid = from_kgid_munged(file->f_cred->user_ns, current_gid());
528 #if ACCT_VERSION == 1 || ACCT_VERSION == 2
529 	/* backward-compatible 16 bit fields */
530 	ac->ac_uid16 = ac->ac_uid;
531 	ac->ac_gid16 = ac->ac_gid;
532 #elif ACCT_VERSION == 3
533 	{
534 		struct pid_namespace *ns = acct->ns;
535 
536 		ac->ac_pid = task_tgid_nr_ns(current, ns);
537 		rcu_read_lock();
538 		ac->ac_ppid = task_tgid_nr_ns(rcu_dereference(current->real_parent), ns);
539 		rcu_read_unlock();
540 	}
541 #endif
542 }
543 
acct_write_process(struct bsd_acct_struct * acct)544 static void acct_write_process(struct bsd_acct_struct *acct)
545 {
546 	struct file *file = acct->file;
547 	const struct cred *cred;
548 	acct_t *ac = &acct->ac;
549 
550 	/* Perform file operations on behalf of whoever enabled accounting */
551 	cred = override_creds(file->f_cred);
552 
553 	/*
554 	 * First check to see if there is enough free_space to continue
555 	 * the process accounting system. Then get freeze protection. If
556 	 * the fs is frozen, just skip the write as we could deadlock
557 	 * the system otherwise.
558 	 */
559 	if (check_free_space(acct) && file_start_write_trylock(file)) {
560 		/* it's been opened O_APPEND, so position is irrelevant */
561 		loff_t pos = 0;
562 		__kernel_write(file, ac, sizeof(acct_t), &pos);
563 		file_end_write(file);
564 	}
565 
566 	revert_creds(cred);
567 }
568 
do_acct_process(struct bsd_acct_struct * acct)569 static void do_acct_process(struct bsd_acct_struct *acct)
570 {
571 	unsigned long flim;
572 
573 	/* Accounting records are not subject to resource limits. */
574 	flim = rlimit(RLIMIT_FSIZE);
575 	current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
576 	fill_ac(acct);
577 	acct_write_process(acct);
578 	current->signal->rlim[RLIMIT_FSIZE].rlim_cur = flim;
579 }
580 
581 /**
582  * acct_collect - collect accounting information into pacct_struct
583  * @exitcode: task exit code
584  * @group_dead: not 0, if this thread is the last one in the process.
585  */
acct_collect(long exitcode,int group_dead)586 void acct_collect(long exitcode, int group_dead)
587 {
588 	struct pacct_struct *pacct = &current->signal->pacct;
589 	u64 utime, stime;
590 	unsigned long vsize = 0;
591 
592 	if (group_dead && current->mm) {
593 		struct mm_struct *mm = current->mm;
594 		VMA_ITERATOR(vmi, mm, 0);
595 		struct vm_area_struct *vma;
596 
597 		mmap_read_lock(mm);
598 		for_each_vma(vmi, vma)
599 			vsize += vma->vm_end - vma->vm_start;
600 		mmap_read_unlock(mm);
601 	}
602 
603 	spin_lock_irq(&current->sighand->siglock);
604 	if (group_dead)
605 		pacct->ac_mem = vsize / 1024;
606 	if (thread_group_leader(current)) {
607 		pacct->ac_exitcode = exitcode;
608 		if (current->flags & PF_FORKNOEXEC)
609 			pacct->ac_flag |= AFORK;
610 	}
611 	if (current->flags & PF_SUPERPRIV)
612 		pacct->ac_flag |= ASU;
613 	if (current->flags & PF_DUMPCORE)
614 		pacct->ac_flag |= ACORE;
615 	if (current->flags & PF_SIGNALED)
616 		pacct->ac_flag |= AXSIG;
617 
618 	task_cputime(current, &utime, &stime);
619 	pacct->ac_utime += utime;
620 	pacct->ac_stime += stime;
621 	pacct->ac_minflt += current->min_flt;
622 	pacct->ac_majflt += current->maj_flt;
623 	spin_unlock_irq(&current->sighand->siglock);
624 }
625 
slow_acct_process(struct pid_namespace * ns)626 static void slow_acct_process(struct pid_namespace *ns)
627 {
628 	for ( ; ns; ns = ns->parent) {
629 		struct bsd_acct_struct *acct = acct_get(ns);
630 		if (acct) {
631 			do_acct_process(acct);
632 			mutex_unlock(&acct->lock);
633 			acct_put(acct);
634 		}
635 	}
636 }
637 
638 /**
639  * acct_process - handles process accounting for an exiting task
640  */
acct_process(void)641 void acct_process(void)
642 {
643 	struct pid_namespace *ns;
644 
645 	/*
646 	 * This loop is safe lockless, since current is still
647 	 * alive and holds its namespace, which in turn holds
648 	 * its parent.
649 	 */
650 	for (ns = task_active_pid_ns(current); ns != NULL; ns = ns->parent) {
651 		if (ns->bacct)
652 			break;
653 	}
654 	if (unlikely(ns))
655 		slow_acct_process(ns);
656 }
657